Safety arrangement for a vehicle using separate sensing and control units

ABSTRACT

A vehicle safety arrangement having a sensor unit ( 7 ) comprising at least one sensor ( 8, 9 ) responsive to acceleration; an actuator ( 13 ) for activating a safety device, the actuator being located remotely from the sensor unit; and a control unit ( 2 ) located remotely from the sensor unit and from the actuator, the control unit having no sensors responsive to acceleration and being operable to receive information from the sensor unit and to transmit an actuating command to the actuator to activate the safety device.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to PCT/SE2003/001622, filed Oct. 21,2003, GB 0 224 429.1, filed Oct. 21, 2002, and GB 0 228 054.3, filedDec. 2, 2002.

FIELD OF THE INVENTION

This invention relates to a safety arrangement for a vehicle, and inparticular concerns an improved arrangement for detecting a crashsituation and controlling at least one safety device, such as anair-bag.

BACKGROUND OF THE INVENTION

Modern vehicle safety systems typically comprise a main control unit,which is the hub of the system. The main control unit comprises one ormore accelerometers to measure the rate of change of velocity of thevehicle, a processor operable to perform a decision algorithm on thesignals output by the accelerometers in order to establish whether acrash situation has occurred and implement a crash algorithm to activateone or more safety devices accordingly, an energy source, normally inthe form of one or more capacitors, storing sufficient ignition energyto activate the safety device, and an ignition circuit, which iscontrolled by the output of the crash algorithm, and which connects thecapacitor(s) to the safety device(s) to deploy the safety device(s) upondetection of a crash situation. The control unit may also comprise meansfor controlling the communications between the control unit and variousexternal units, and have a diagnostic function.

Due to the fact that the control unit comprises accelerometers, thecontrol unit must be physically located in a part of the vehicle wherethe sensed acceleration will be representative of the acceleration ofthe vehicle as a whole. The ideal location for this purpose is thecentral tunnel of the vehicle, which comprises a ridge running along thecentre of the floor of the chassis of the vehicle, and in many knownsystems the control unit is mounted on an upper surface of the controltunnel, i.e. within the vehicle cabin.

Due to the number of components contained in the control unit, thecontrol unit is rather large and heavy. It may, therefore, be difficultto allocate sufficient space to the control unit on the central tunnelof the vehicle, which typically also carries other components such asthe gear stick.

In addition, a heavy control unit will generate substantial vibrationwhile the vehicle is moving, and this is likely to compromise theaccuracy of the signal output by accelerometers provided therein.

It is an object of the present invention to alleviate one or more of theabove difficulties.

SUMMARY OF THE INVENTION

Accordingly, one aspect of the present invention provides a vehiclesafety arrangement, the arrangement includes a sensor unit having atleast one sensor responsive to acceleration, the sensor unit beinglocated substantially along a central longitudinal line of the vehicle.

The safety arrangement further includes an actuator for activating asafety device, the actuator being located remotely from the sensor unit;and a control unit located remotely from the sensor unit and from theactuator, the control unit being operable to receive information fromthe sensor unit and to transmit an actuating command to the actuator toactivate the safety device. The control unit of this invention does nothave sensors responsive to acceleration, but includes a signal processorfor sampling data gathered by sensors of the sensor unit.

Preferably, the sensor unit is located on a central tunnel of thevehicle.

Conveniently, the sensor unit comprises at least two sensors responsiveto acceleration, which are configured to measure at least longitudinaland lateral acceleration of the vehicle.

Advantageously, the at least one sensor responsive to acceleration isconfigured to measure vertical acceleration of the vehicle.

Conveniently, the signal processor is operable to transmit the sampleddata to the control unit.

Advantageously, the signal processor is operable to perform a crashalgorithm, which causes the signal processor to instruct the controlunit to transmit the actuating command to the actuator.

Alternatively, the signal processor is operable to receive the output ofa decision algorithm, which determines whether the vehicle is in a crashsituation.

Preferably, the decision algorithm is performed in the control unit.

Conveniently, the signal processor is operable to receive data fromother remote sensors.

Advantageously, the sensor unit comprises one or more sensors operableto measure an angular velocity of the vehicle around a longitudinal axisthereof.

Preferably, the actuator comprises an ignitor for igniting a charge toactivate the safety device.

Conveniently, the control unit comprises one or more capacitorsconfigured to store sufficient energy to cause the actuator to activatethe safety device.

Advantageously, the discharge of the one or more capacitors comprisesthe actuation command.

Preferably, the actuator is located in a unit that also comprises acapacitor configured to store energy to activate the safety device, thecapacitor being discharged to activate the safety device in response tothe actuation command.

Conveniently, the safety arrangement further comprises at least one leftside sensor on a left side of the vehicle and at least one right sidesensor on a right side of the vehicle.

Advantageously, the control unit is connected to a main battery of thevehicle, and supplies power to the sensor unit and the actuator.

Preferably, the sensor unit has a smaller volume than that of thecontrol unit.

Conveniently, the sensor unit has a volume less than half that of thecontrol unit.

Advantageously, the sensor unit has a smaller mass than that of thecontrol unit.

Preferably, the mass of the sensor unit is less than half that of thecontrol unit.

Conveniently, the sensor unit is provided on a single microchip.

Advantageously, the sensor unit comprises a processor.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention may be more readily understood,embodiments thereof will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 shows a first safety arrangement embodying the present invention;

FIG. 2 shows a second safety arrangement embodying the presentinvention;

FIG. 3 shows a third safety arrangement embodying the present invention;and

FIG. 4 shows a fourth safety arrangement embodying the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a schematic representation of a first safetyarrangement 1 embodying the present invention is shown. The first safetyarrangement 1 comprises a control unit 2 which has a processor 3. Theprocessor 3 is, as discussed above, operable to apply a decisionalgorithm to signals received from sensors (described below), todetermine from these signals whether a crash situation has occurred.Such algorithms are known in the art.

The control unit 2 further comprises an ignition circuit 4, which isoperable to send an actuation command (in this case in the form of anignition energy pulse) to a safety device of the vehicle, for instancean air-bag, as will be described in more detail below. The ignitioncircuit 4 is connected to one or more substantial capacitors 5 a, whichare charged with sufficient energy to activate the safety device, andwill transmit the stored energy to the safety device upon receipt of atrigger signal from the processor 3. Alternatively, the ignition energycould be taken directly from the vehicle battery, although the batterymay become disconnected from the safety arrangement 1, which couldresult in a failure of the safety device to deploy.

Finally, the control unit 2 comprises a voltage regulator 5 b, whichreceives power from the vehicle battery 6, or from an alternative powersource, and regulates the voltage for charging the capacitors but couldalso provide power to the processor 3, and other components of the firstsafety arrangement 1.

It will be appreciated that the control unit 2 will be relatively largeand heavy, particularly due to the presence of the capacitors and theignition circuit 4, which normally comprises two switches for eachsafety device. The switches are respectively closed in response to anarming signal and to the trigger signal.

The safety arrangement 1 further comprises a sensor unit 7, whichcomprises a pair of accelerometers 8 and 9 one of which is orientated soas to measure longitudinal acceleration a_(x) of the vehicle, and theother of which is orientated to measure lateral acceleration a_(y) ofthe vehicle. The sensor unit 7 comprises a signal processor 10, whichreceives outputs from the accelerometers 8 and 9 and manipulates thedata to be in a suitable form for feeding to the processor 3 of thecontrol unit 2.

Left and right sensors 11 and 12 respectively (which may also beaccelerometers) are also provided, separately from the sensor unit 7,and the left and right sensors 11 and 12 are configured to be located onrespective left and right hand sides 101 and 102 (schematicallyillustrated) of the vehicle to provide additional information that maybe useful in determining whether or not the vehicle has encountered acrash situation, or in providing information on the type of crash thathas occurred.

The safety arrangement 1 also comprises one or more actuators 13, in theform (in this example) of squibs or other devices such as relays which,upon activation thereof may, by way of example, inflate air-bags andrelease belt pre-tensioners.

As discussed above, it is important for the sensor unit 7 to bephysically located on the vehicle in a position where the sensedacceleration will be representative of the acceleration of the vehicleas a whole. Hence, the sensor unit 7 is positioned substantially along acentral longitudinal line of the vehicle. In advantageous embodiments ofthe invention, the sensor unit 7 is located on the central tunnel 103(schematically illustrated) of the vehicle, and in such embodiments thesensor unit 7 may be directly attached by any suitable means to an upperor lower surface of the central tunnel, or to a covering thereof. Thesensor unit 7 may be located within the cabin of the vehicle.

However, the control unit 2, which comprises rather heavier components,is located remotely from the sensor unit 7 and indeed may be placed inany suitable location on the vehicle, not necessarily anywhere near thecentral longitudinal line thereof (e.g. on a different part of thetunnel or behind the dashboard).

The control unit 2 communicates with the sensor unit 7 over a sensorcommunication line 14, which may take any suitable form.

The remote location of the control unit 2 from the sensor unit 7 meansthat it is not necessary to house the control unit 2 in the centraltunnel of the vehicle, thus alleviating the difficulty discussed above.

In addition, the relatively large vibrations that the control unit 2will undergo during movement of the vehicle will not affect the sensorunit 7, which will therefore provide more reliable data regarding theacceleration of the vehicle.

The control unit 2 is also located remotely from the actuator 13, andcommunicates therewith over an activation communication line 15. Asdiscussed above, the control unit 2 comprises an ignition circuit 4connected to capacitors 5 a charged with sufficient energy to activatethe actuator 13 (for instance, to activate one or more ignitors toignite the squibs), and in this embodiment the activation communicationline 15 may simply comprise a power line, with the control unit 2initiating activation of the actuator 13 by discharging the capacitorsalong the power line.

It will be appreciated that, with the above arrangement, the volume andmass of the components that are located in the sensor unit 7 on thecentral tunnel of the vehicle are kept to an absolute minimum, with thelarger, more massive components being conveniently located elsewhere inthe vehicle in the control unit 2.

FIG. 2 shows a second safety arrangement 16 embodying the presentinvention. Common components between the first safety arrangement 1discussed above and the second safety arrangement 16 are designated bylike reference numerals.

In the second safety arrangement 16, the processing unit 3 in thecontrol unit 2 receives data from the left and right sensors 11,12, andperforms signal processing, the output of which is sent to the signalprocessor 10, which now implements the main crash algorithm and hencedecides whether the safety device is to be deployed. The signalprocessor 10 will, upon receiving a signal from the processing unit 3,perform the crash algorithm, and will (if appropriate) instruct theignition circuit 4 to send an actuation command to the actuators 13.

The second safety arrangement 16 also comprises a third sensor 17 in thesensor unit 7, this third sensor 17 being position to allow measurementof movement of the vehicle around the roll axis (angular velocity,ω_(x)). Components of second safety arrangement 16, along withadditional embodiments described below, include components common withthose of the first safety arrangement 1, and are identified by likereference numbers.

FIG. 3 shows a third safety arrangement 18 embodying the presentinvention. The third safety arrangement 18 comprises further sensors 19,which measure parameters of the car other than the acceleration thereof.For instance, the further sensors 19 may detect whether seat beltbuckles are engaged, or may otherwise detect the presence of an occupantin a given seat of the vehicle, for instance by the weight exerted onthe seat, or may measure the position of the seat or a part thereof(such as the headrest). The further sensors 19 may also gatherinformation relating to the speed of the vehicle. The information outputby the further sensors 19 is passed to the control unit 2 via aninformation bus 20, which allows communication between the control unit2 and any other remote crash sensors (for instance the left and rightsensors 11 and 12) and the actuator 13.

The information gathered by the further sensors 19 allows the processor3 of the control unit 2 to arrive at a more informed decision regardingwhether to activate the safety device. For instance, if the furthersensors 19 detect that the passenger seat of the vehicle is unoccupiedduring a crash, the control unit 2 may prevent the triggering of apassenger-side air-bag, since this is unlikely to offer protection tothe occupants of the vehicle, and may hinder efforts to leave thevehicle, or remove people from the vehicle, following a crash.

Also, in the third safety arrangement 18, the sensor unit 7 is providedon a single microchip, and it will be appreciated that this arrangementfurther reduces the size and mass of the components that are to belocated in the central tunnel of the vehicle.

With reference to FIG. 4, a fourth safety arrangement 21 embodying thepresent invention is shown. The fourth safety arrangement 21 is similarto the third safety arrangement 18, however each safety device isprovided with a unit comprising a capacitor 5 a, an ignition circuit 4and an actuator 13, and the information bus 20 continuously transmitspower from the control unit 2 to the capacitors and other remote unitsof the arrangement 21, including for instance the sensor unit 7. The bus20 also transmits the actuation command, now in form of a triggersignal, from the processor 3 to the ignition circuits. If an armingswitch is used in circuit 4, an arming signal will also be sent. Thesensor unit could also comprise a vertical accelerometer 22 to measurevertical acceleration a_(z).

It will be understood that the present invention provides an improvedsafety arrangement, providing favourable distribution of componentsaround a vehicle, while improving the accuracy with which a crashsituation may be detected.

As a person skilled in the art will readily appreciate, the abovedescription is meant as an illustation of the implementation of theprinciples of this invention. This description is not intended to limitthe scope or application of this invention in that the invention issusceptible to modificatioon, variation and change, without departingfrom the spirit of this invention, as defined in the following claims.

The invention claimed is:
 1. A vehicle safety arrangement for a vehicle,the arrangement comprising: a sensor unit comprising at least one sensorresponsive to acceleration, the sensor unit being located substantiallyalong a central longitudinal line of the vehicle, the sensor unit havinga signal processor for sampling data gathered by the at least onesensor; an actuator for activating a safety device, the actuator beinglocated remotely from the sensor unit; and a control unit locatedremotely from the sensor unit and from the actuator and away from thecentral longitudinal line, the control unit being operable to receivesensor signals from remote sensors located away from the sensor unit andthe control unit and to provide data from the remote sensors to thesignal processor of the sensor unit for performing a crash algorithm,the control unit being operable to receive information from the sensorunit and to transmit an actuation command to the actuator to activatethe safety device, wherein the control unit comprises no sensorresponsive to acceleration; wherein the signal processor operates toperform the crash algorithm, which causes the signal processor toinstruct the control unit to transmit the actuation command to theactuator.
 2. A safety arrangement according to claim 1, wherein thesensor unit is located on a central tunnel of the vehicle.
 3. A safetydevice according to claim 1, wherein the sensor unit comprises at leasttwo sensors responsive to acceleration, which are configured to measureat least longitudinal and lateral acceleration of the vehicle.
 4. Asafety arrangement according to claim 1, wherein the at least one sensorresponsive to acceleration is configured to measure verticalacceleration of the vehicle.
 5. A safety arrangement according to claim1, wherein the signal processor is operable to receive data fromadditional remote sensors.
 6. A safety arrangement according to claim 1,wherein the sensor unit comprises one or more sensors operable tomeasure an angular velocity of the vehicle around a longitudinal axisthereof.
 7. A safety arrangement according to claim 1, wherein theactuator comprises an ignitor for igniting a charge to activate thesafety device.
 8. A safety arrangement according to claim 1, wherein thecontrol unit comprises one or more capacitors configured to storesufficient energy to cause the actuator to activate the safety device.9. A safety arrangement according to claim 8, wherein the discharge ofthe one or more capacitors comprises the actuation command.
 10. A safetyarrangement according to claim 1, wherein at least one actuator islocated in a unit that also comprises a capacitor configured to storeenergy to activate the safety device, the capacitor being discharged toactivate the safety device in response to the actuation command.
 11. Asafety arrangement according to claim 1, further comprising at least oneleft side sensor on a left side of the vehicle and at least one rightside sensor on a right side of the vehicle.
 12. A safety arrangementaccording to claim 1, wherein the control unit is connected to a mainbattery of the vehicle, and supplies power to the sensor unit and to theactuator.
 13. A safety arrangement according to claim 1, wherein thesensor unit has a smaller volume than that of the control unit.
 14. Asafety arrangement according to claim 1, wherein the sensor unit has avolume less than half that of the control unit.
 15. A safety arrangementaccording to claim 1, wherein the sensor unit has a smaller mass thanthat of the control unit.
 16. A safety arrangement according to claim15, wherein the mass of the sensor unit is less than half that of thecontrol unit.
 17. A safety arrangement according to claim 1, wherein thesensor unit is provided on a single microchip.